1. Field of the Invention
The present invention relates to image forming apparatus such as a laser printer.
2. Description of the Related Art
In a conventional image forming apparatus such as a laser printer, a desired electrostatic latent image is formed on the surface of an image carrier such as a photoconductor drum. Next, to the image carrier surface where the electrostatic latent image is formed, toner is transferred to form a toner image by a developing unit. The formed toner image is transferred onto a recording sheet. Thus, an image is formed.
Examples of methods for transferring a toner image onto a recording sheet include a method in which a toner image is transferred directly to a recording sheet conveyed through a transfer belt, and a method in which a toner image is once transferred onto a transfer belt (generally referred to as “intermediate transfer belt”) so as to form an image on the intermediate transfer belt, and then the image is secondarily transferred onto a recording sheet.
In order to obtain a stable and good image quality, it is important to transfer the toner uniformly from the developing unit to the image carrier surface in such a series of steps of image formation.
To this end, in the image forming apparatus in the background art, pressure is applied between the developing unit and the image carrier, and a pressure mechanism using a spring or the like is provided for keeping the pressure constant. (e.g. see JP-A-7-072782)